The present invention relates to an art for communication in an environment where identification information dynamically changes in a network, and more particularly, to an art for enabling communication by following a change in identification information even when no name server is available.
In a network system using a TCP/IP, an IP address is dynamically assigned to a device which is connected to a network by utilization of the art of DHCP (Dynamic Host device Configuration Protocol). In relation to the DHCP, a DHCP server assigns IP addresses to devices which have been connected to the network, in the sequence in which the devices have been connected to the network. When the device assigned a particular IP address leaves the network, the DHCP server recovers the IP address assigned to the device and possibly re-uses the IP address by assigning the IP address to another device.
Consequently, when a device having once been assigned an IP address upon connection with the network and having left the network is again connected to the network, the device is not guaranteed to be assigned the same IP address as that assigned previously. When communication is performed by using a TCP/IP, the IP address becomes identification information in the network. Hence, if the IP address is changed, communication cannot be continued unless a newly-assigned IP address is acquired. For instance, in a situation where a host device and a printer are connected to a network, when the IP address of the printer is changed as a result of the power of the printer being turned off and again turned on, the host device cannot perform printing by use of the printer in subsequent operations, unless the host device acquires a new IP address of the printer
Therefore, in a widely practiced art, the problem of the address is solved by providing a DNS (Domain Name System) server in the network in order to avoid occurrence of such a situation, by means of following a change in the IP address (e.g., JP-A-11-355303).
In a LAN (Local Area Network) environment of a given scale or larger, even when an attempt is made to solve the problem of addresses by introduction of a DNS server such as that mentioned above, an advantage appropriate to costs incurred by introduction and management can be expected. However, in a LAN environment of extremely small scale, such as that found in an ordinary home, introduction of a name server such as a DNS is not realistic for various reasons, such as introduction costs or a deficiency in network management skills.